Synergistic compositions containing a polyoxyethylene sorbitol hexaoleate and their use

ABSTRACT

The present invention relates to certain processes and compositions useful for inhibiting the growth of slime in water and, in particular, water used for industrial purposes; for example, in the manufacture of wood pulp, in the manufacture of paper, in cooling water systems, and in effluent water treatment. The novel processes and compositions of the present invention are processes of mixtures which show unexpected synergistic activity against microorganisms, including bacteria, (in particular Aerobacter aerogenes) fungi, and algae, which produce slime in aqueous systems which are objectionable from either an operational or aesthetic point of view. Specifically, the invention is directed to the use of compositions comprising a combination 1,3-dichloroacetone oxime acetate and polyoxyethylene sorbitol hexaoleate having an average of 40 oxyethylene groups.

This application is a continuation-in-part of application Ser. No.545,678 filed Jan. 30, 1975 now abandoned.

BACKGROUND OF THE INVENTION

The formation of aqueous slimes by microorganisms is a problem which isencountered in many systems. For example, the problem is not only foundin natural waters such as lagoons, lakes, ponds, etc. and confinedwaters as in pools, but also in such industrial systems as cooling watersystems, air washer systems and pulp and paper mill systems. All possessconditions which are conducive to the growth and reproduction ofslime-forming microorganisms. In both once-through and recirculatingcooling systems, for example, which employ large quantities of water asa cooling medium, the formation of slime by microorganisms is anextensive and constant problem.

Airborne organisms are readily entrained in the water from coolingtowers and find this warm medium an ideal environment for growth andmultiplication. Aerobic and heliotropic organisms flourish on the towerproper while other organisms colonize and grow in such areas as thetower sump and the piping and passages of the cooling system. The slimeformation not only aids in the deterioration of the tower structure inthe case of wooden towers, but also by its deposition on metal surfaces,promotes corrosion. In addition, slime carried through the coolingsystem plugs and fouls lines, valves, strainers, etc. and deposits onheat exchange surfaces. In the latter case, the impedance of heattransfer can greatly reduce the efficiency of the cooling system.

In pulp and paper mill systems, slime formed by microorganisms iscommonly encountered causing fouling or plugging thereof. The slime alsobecomes entrained in the paper produced to cause breakouts on the papermachines with consequent work stoppages and the loss of production timeand/or is responsible for unsightly blemishes in the final product whichresult in rejects and wasted output. The previously discussed problemshave resulted in the extensive utilization of biocides in cooling waterand pulp and paper mill systems. Materials which have enjoyed widespreaduse in such applications include chlorine, chlorinated phenols,organo-bromines, and various organo-surfur compounds. All of thesecompounds are generally useful for this purpose but each is attended bya variety of impediments. For example, chlorination is limited both byits specific toxicity for slime-forming organisms at economic levels andby the tendency of chlorine to react which results in the expenditure ofthe chlorine before its full biocidal function is achieved. Otherbiocides are attended by odor problems and hazards in respect tostorage, use or handling which limit their utility. To date, no onecompound or type of compound has achieved a clearly establishedpredominance in respect to the applications discussed. Likewise,lagoons, ponds, lakes, and even pools, either used for pleasure purposesor used for industrial purposes for the disposal and storage ofindustrial wastes, become, during the warm weather, beseiged by slimedue to microorganism growth and reproduction. In the case of therecreational areas the problem of infection is obvious. In the case ofindustrial storage or disposal of industrial materials, themicroorganisms cause additional problems which must be eliminated priorto the materials use or the waste is treated for disposal.

Naturally, economy is a major consideration in respect to all of thesebiocides. Such economic considerations attach to both the cost of thebiocide and the expense of its application. The cost performance indexof any biocide is derived from the basic cost of the material, itseffectiveness per unit of weight, the duration of its biocidal orbiostatic effect in the system treated, and the ease and frequency ofits addition to the system treated. To date, none of the commerciallyavailable biocides have exhibited a prolonged biocidal effect. Instead,their effectiveness is rapidly reduced as the result of exposure tophysical conditions such as temperature, association with ingredientscontained by the system toward which they exhibit an affinity orsubstantivity, etc., with a resultant restriction or elimination oftheir biocidal effectiveness.

As a consequence, the use of such biocides involves their continuous orfrequent addition to systems to be treated and their addition to aplurality of points or zones in the systems to be treated. Accordingly,the cost of the biocide and the labor cost of such means of applying itare considerable. In other instances, the difficulty of access to thezone in which slime formation is experienced precludes the effective useof a biocide. For example, if in a particular system there is no accessto an area at which slime formation occurs the biocide can only beapplied at a point which is upstream in the flow system. However, thephysical or chemical conditions, e.g., chemical reactivity, thermaldegradation, etc. which exist between the point at which the biocide maybe added to the system and the point at which its biocidal effect isdesired render the effective use of a biocide impossible.

Similarly, in a system experiencing relatively slow flow, such as apaper mill, if a biocide is added at the beginning of the system, itsbiocidal effect may be completely dissipated before it has reached allof the points at which this effect is desired or required. As aconsequence, the biocide must be added at a plurality of points, andeven then a graduated biocidal effect will be experienced between onepoint of addition to the system and the next point downstream at whichthe biocides may be added. In addition to the increased cost ofutilizing and maintaining plural feed points, gross ineconomies inrespect to the cost of the biocide are experienced. Specifically, ateach point of addition, an excess of the biocide is added to the systemin order to compensate for that portion of the biocide which will beexpended in reacting with other constituents present in the system orexperience physical changes which impair its biocidal activity.

It is an object of the present invention to provide methods andcompositions for controlling slime-forming microorganisms, in particularAerobacter aerogenes in aqueous systems such as cooling water systemsand pulp and paper mill systems, and for controlling slime formation ormicroorganism populations in aqueous bodies in general. Moreover,another object of the invention is the provision of methods andcompositions for controlling slime-forming microorganisms in any aqueoussystem which is conducive to the growth and reproduction of Aerobacteraerogenes and, in particular, cooling water and paper and pulp millsystems. These systems employ a combination of 1,3-dichloroacetone oximeacetate and polyoxyethylene sorbitol hexaoleate having an average of 40oxyethylene groups.

In practice of the invention, the combination is added to the particularsystem being treated, for example, cooling water systems, paper and pulpmill systems, pools, ponds, lagoons, lakes, etc. in a quantity adequateto control the slime-forming microorganisms and in particular Aerobacteraerogenes, which are contained by, or which may become entrained in, thesystem which is treated. It has been found that such compositions andmethods control the growth and occurrence of such fungal, bacterial andalgal microorganism as may populate these particular systems.

1,3-dichloroacetone oxime acetate, as disclosed in U.S. Pat. 3,733,419,is available commercially as Stauffer R-22938 (Stauffer Chemical Co.)and polyoxyethylene sorbitol hexaoleate having an average of 40oxyethylene groups is also available commercially as Atlas G1086 or asPOE-40 from Glyco Chemicals Inc.

As earlier stated, the inventive compositions are comprised of thelatter compounds, either compound being present in such a quantity as toimpart a synergistic behavior to the combination as a whole. Thedesirable weight ratio of the Stauffer R-22938 to the specifichexaoleate ranges from about 95:5 to about 5:95 with a range of 80:20 to5:95 being a preferred range. When these two ingredients are mixed, theresulting mixtures possess a higher degree of slimicidal activity thanthe individual ingredients comprising the mixture. Accordingly, it istherefore possible to produce a more effective slime-control agent thanthe use of either ingredient alone. Because of the enhanced activity ofthe mixture, the total quantity of the biocide required for an effectivetreatment may be reduced. In addition, the high degree of biocidaleffectiveness which is provided by each of the ingredients may beexploited without use of the higher concentrations of each.

To demonstrate the synergism which is provided by the inventivecombinations of compounds, the data as set forth in the Table below wasdeveloped.

EXAMPLE 1

Synergism was demonstrated by adding Compound A and Compound B invarying ratios and over a range of concentrations to liquid nutrientagar medium (Tryptone Glucose Extract Agar) at approximately 50° C.After the medium had solidified in Petri plates, it was inoculated withsuspension of Aerobacter aerogenes. Following two days incubation, thelowest concentration of each ratio which prevented growth on the agarmedium was taken as the end point. End points for the various mixtureswere then compared with end points for the pure active ingredientsworking alone in concomitantly prepared agar medium plates. Synergismwas determined by the method described by F. C. Kull, P. C. Eisman, H.D. Sylwestrowicz and R. L. Mayer, APPLIED MICROBIOLOGY, 9, 538-41(1961), and the relationships, ##EQU1## where, ^(Q) a = Quantity ofCompound A, acting alone, producing an end point

^(Q) b = Quantity of Compound B, acting alone, producing an end point

^(Q) A = Quantity of Compound A, in the mixture, producing an end point

^(Q) B = Quantity of Compound B, in the mixture, producing an end point

For mixtures of Compounds A and B, and for Compound A and B actingalone, the following results were observed.

Summary of synergistic activity of varying percentages of Compound A andCompound B:

Synergistic Combination

Compound A: 1,3-dichloroacetone oxime acetate (Stauffer R-22938)

Compound B: Polyoxyethylene sorbitol hexaoleate having an average of 40oxyethylene groups (POE-40)

                                      TABLE I                                     __________________________________________________________________________    TEST ORGANISM                                                                 AEROBACTER AEROGENES*                                                         Weight ratio of A to B First Test Series                                                   Quantities Producing End Points (ppm)  Q.sub.A Q.sub.B                      mixture                                                                                             ##STR1##                                     __________________________________________________________________________    100/0      14.0   --     14.0   --   --   --                                  95/5       13.3   0.7    14.0   .95  .001 .95                                 50/50      10.0   10.0   20.0   .71  .002 .71                                 5/95       10.0   190.0  200.0  .71  .04  .75                                 0/100      --     5000   5000   --   --   --                                  Second Test Series                                                            80/20      12     3      15     .87  0.0003                                                                             .87                                 __________________________________________________________________________     *Currently referred to as Klebsiella pneumonia                           

The mode of establishing the synergistic behavior of the compositions ofthe present invention is a widely used and an industrially acceptableprocedure. Although it is believed that the above is sufficient inexplaining the procedure, for a further description thereof referencecan be made to U.S. Pat. No. 3,231,509 and its file history where dataof this nature was considered to be acceptable. Moreover, the article byKull et al published in APPLIED MICROBIOLOGY, 9, 538-541, will furnishadditional information in this regard.

For the testing to ascertain synergistic behavior, Aerobacter aerogenes(now currently referred to as Klebsiella pneumonia) was favored sincethis microorganism is found to exist and be most troublesome in pulp andpaper producing processes, as well as in cooling towers. Moreover, thismicroorganism is difficult to control and/or kill and accordingly itsexistence does give rise to troublesome slime. In view of the foregoing,it can then be appreciated that since Aerobacter aerogenes is prevalentin most slime-affected systems and since this microorganism is difficultto control or kill, that once control of this microorganism ismaintained, then for all practical purposes the total microorganismpopulation with its different types is considered controlled.

When the inventive compositions are employed in the treatment of coolingor paper mill water, they are preferably utilized in the form ofrelatively dilute solutions or dispersions. For example, a preferredsolution comprises between 5 to 65% by weight of the synergisticcombination in admixture with various solvents and solubilizing agents.

Surfactants such as the alkylaryl polyether alcohols, polyetheralcohols, alkyl benzene sulfonates and sulfates, and the like, may alsobe employed to enhance the dispersibility and stability of theseformulations. The foregoing solutions of the biocidal compositions areutilized in order to insure the rapid and uniform dispersibility of thebiocides within the industrial water which is treated. It has been foundthat either aqueous or non-aqueous solvents are suitable in thepreparation of compositions of the invention. For example, organicsolvents such as methyl cellosolve and aliphatic and aromatichydrocarbons, e.g., kerosene, can be used quite successfully. Based uponthe synergism study as outlined above, it was ascertained that in thetreatment of paper mill and cooling water, effective biocidal action isobtained when the concentration or treatment level of the combination oradmixture of biocides is between 0.5 parts per million to 1000 parts permillion, and preferably between 1 and 100 parts per million, based uponthe total content of the system treated, such as the total quantity ofcooling water or paper mill water and the severity of the problem.

The compositions may also be utilized for the preservation of slurriesand emulsions containing carbohydrates, proteins, fats, oils, etc.Dosage levels for this purpose range in the vicinity of 0.01% to 5%.

The compositions of the invention which can be prepared by merelycombining the respective ingredients and mixing thoroughly at standardconditions may be fed continuously to the treated system, e.g., by meansof a metered pump, or may be fed periodically at intervals calculated tocontrol the growth of slime-forming organisms in the system. Naturally,in the treatment of cooling water the feeding of the inventivecompositions must be designed to compensate for blow-down in thosesystems which employ that expedient.

As would be expected, the inventive composition may be added to thecooling water or paper and pulp mill systems at any convenient point.Naturally, in once-through or non-circulating systems, the compositionmust be added upstream from the point or points at which microorganismcontrol is desired. In circulating systems or pulp and paper systems,the compositions may be added at any point provided that the time lapseand the conditions experienced between point of addition and the pointat which the effect of the composition is experienced are not so drasticas to result in the neutralization of the effect of the composition.

SLIME CONTROL EFFECTIVENESS

The inventive methods and materials were tested with respect to theirperformance in the control of slime formation in industrial systems. Inthis test an industrial recirculating water was obtained from a systemwhich was currently experiencing problems in respect to the formation ofslime by microorganisms. Such tests do not demonstrate the efficiency ofthe biocide employed with respect to specific species of microorganisms,but instead supply a practical demonstration of the efficacy of thebiocide tested in relation to those communities of microorganisms whichhave evidenced their ability to form slime in actual industrial systems.

In testing of recirculating water samples, a substrate evaluation wasemployed. In such testing, identical portions of water samples aretreated with varying concentrations of biocide and two portions are leftuntreated to serve as controls. The control portions are plated fortotal count at the beginning of biocide treatment and all portions areplated for total count at some suitable time period(s) after beginningbiocide treatment. Using the counts obtained from the platings, thepercentage kill (based on the initial control count) may be calculated.In the following example, the water sample was taken from a coolingtower located in north-eastern Pennsylvania.

For the purposes of comparison, a composition of this invention wasevaluated with two recognized commercial biocides.

                  TABLE II                                                        ______________________________________                                                          Quantity of Percent Kill                                    Biocidal Material Biocide (ppm)                                                                             After 3 Hours                                   ______________________________________                                        Stauffer R-22938 (5%)                                                                           5                 99+                                                         10                99+                                       POE-40 (5%)       25                99+                                                         50                99+                                       Dimethylformamide 90%                                                                           100               99+                                       Pentachlorophenol (10% Active)                                                                  5                 14                                                          10                37                                                          25                68                                                          50                75                                                          100               87                                        Sodium dimethyldithiocarbamate                                                                  5                  5                                        (10% Active)      10                37                                                          25                46                                                          50                44                                                          100               15                                        ______________________________________                                    

EFFICACY RELATIVE TO FUNGI

In order to ascertain whether in fact the inventive compositions wereeffective in controlling fungi, evaluations were made following theprocedure described by Shema et al, JOURNAL FOR THE TECHNICALASSOCIATION OF THE PULP AND PAPER INDUSTRY, 36, 20A-30A, 1953. Thedescribed procedure generally entails incorporating the biocide undertest in a nutrient substrate such as agar, malt, etc. and pouring theresulting medium in a Petri dish and allowing the medium to solidify. Abutton of fungus inoculum is placed on the surface of the solidifiedmedium and the medium is incubated for a period of 14 days. After theperiod, the diameter of the colony is measured and compared with thediameter of the button of inoculum originally placed upon the surface.If there is no increase in the diameter, the growth of the fungus isconsidered to be completely inhibited and the treatment level whicheffectuates this is considered the inhibitory concentration.

The fungi species utilized as the test microorganism to evaluate theefficacy of the present composition were Penicillium expansum andAspergillus niger. The study revealed that the above 10% activecomposition of this invention inhibited the growth of Pennicilliumexpansum at a treatment level of 400 ppm and 600 ppm completelyinhibited the growth of Aspergillus niger.

BACTERICIDAL EFFECTIVENESS

The bactericidal effectiveness of the 1/1 mixture of the two componentsof this invention as earlier described (10% Active) is demonstrated bythe following data in which the inhibiting power is shown in comparisonwith a commercial biocide. Aerobacter aerogenes was employed as the testorganism and a substrate technique was utilized. Specifically, thebiocidal mixture was added in gradually increasing quantities tonutrient agar media which was then innoculated with Aerobacteraerogenes. The preparation was then incubated for 48 hours. The valuesbelow indicate the quantity of biocide required to achieve completeinhibition of the growth of the test organism. The biocideSlime-Trol.sup.(R) RX-38 is available commercially from BetzLaboratories, Inc. and contains as active ingredients about 5% methylenebisthiocyanate and about 17% hexachloro dimethyl sulfone by weight.

    ______________________________________                                        Biocide Materials   Inhibition quantity (ppm)                                 ______________________________________                                        1.  Stauffer R-22938 (5%)                                                                              200                                                      POE-40 (5%)                                                                   Inert Dimethylforamide (90%)                                              2.  Betz Slime-Trol.sup.(R) RX-38 (100%)                                                               30                                                   ______________________________________                                    

Accordingly, since the waters of pulp and paper mills and the water ofcooling water systems generally predominately contain bacteria such asAerobacter aerogenes and some fungi such as Penicillium expansum andAspergillus niger, it is apparent from the foregoing evaluations andstudies that the inventive composition will effectuate the claimedobjective of controlling microorganisms of aqueous systems.

It should be noted that while the preponderance of evidence has beenderived from the treatment of samples like those found in paper and pulpmill aqueous systems or cooling water systems, the compositions andmethods of the present invention are broadly applicable to the treatmentof aesthetic waters as well as industrial waters which are plagued bydeposits formed by slime-forming organisms, or by the very presence ofsuch organisms.

Having thus described the invention what is claimed is:
 1. A compositionfor controlling the growth of the microorganism Aerobacter aerogeneswhich comprises a mixture of 1,3-dichloroacetone oxime acetate andpolyoxyethylene sorbitol hexaoleate having an average of 40 oxyethylenegroups wherein the weight ratio of the acetate to the hexaoleate rangesfrom about 95:5 to about 5:95 respectively.
 2. The composition of claim1 where said ratio is about 50:50.
 3. A composition of claim 1 whereinthe weight ratio of the acetate to the hexaoleate ranges from about80:20 to about 5:95 respectively.
 4. A method for controlling the growthof the microorganism Aerobacter aerogenes in an aqueous system whichcomprises adding to said system a growth inhibiting amount of acomposition comprised of a mixture of 1,3-dichloroacetone oxime acetateand polyoxyethylene sorbitol hexaoleate having an average of 40oxyethylene groups wherein the weight ratio of the acetate to thehexaoleate ranges from about 95:5 to about 5:95 respectively.
 5. Amethod of claim 4 wherein the weight ratio of acetate to the hexaoleateranges from about 80:20 to about 5:95 respectively.
 6. The method ofclaim 5 where said ratio is about 50:50.
 7. The method of claim 5wherein said composition is added to said system in an amount of from0.1 to about 1000 parts per weight of said composition per million partsby weight of said aqueous system.
 8. The method of claim 7 where saidcomposition is added in an amount from about 1 to about 100 parts permillion of said aqueous system.
 9. The method of claim 8 wherein theaqueous system is that of a cooling water system.
 10. The method ofclaim 8 wherein the aqueous system is that of a pulp and paper millsystem.